Results of the INR DTL series crowbar system testing
In the earlier paper description of existing at INR DTL crowbar system and some proposals, increasing its efficiency, were considered. Really it was a question of replacement of the bypass crowbar by the series crowbar system. The last one can be used as RF exciting of accelerator cavities is realiz...
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irk-123456789-170042011-02-18T12:08:33Z Results of the INR DTL series crowbar system testing Kvasha, A.I. Lopatnikov, Yu.M. Физика и техника ускорителей In the earlier paper description of existing at INR DTL crowbar system and some proposals, increasing its efficiency, were considered. Really it was a question of replacement of the bypass crowbar by the series crowbar system. The last one can be used as RF exciting of accelerator cavities is realized by means of vacuum tube power RF amplifier (PA) with plate pulse supply. At that, vacuum tube has to be used in the anode modulator regardless of the method of RF power control. For the last year the new series crowbar system, using the possibilities of the "hard" modulator, was installed at all DTL RF systems of the INR accelerator. The system was successfully tested during 700 hours of continuous accelerator operation. Some peculiarities and results of new system functioning are discussed. Ранее рассмотрены особенности работы параллельной тиристорной защиты, предназначенной для защиты от пробоев мощных ламп в выходных каскадах системы ВЧ-питания начальной части ускорителя. В этой системе при возникновении пробоя через 10 мкс запускается тиристорная сборка, осуществляющая полный разряд накопителя в аноде модуляторной лампы. Предложена принципиально новая последовательная система защиты, лишённая недостатков существующей параллельной тиристорной защиты, использующая возможности модулятора с регулируемой лампой. В новой системе защиты при возникновении пробоя через 5…7 мкс происходит запирание модуляторной лампы с последующим прерыванием запуска на несколько секунд. За это время сохраняется настройка резонатора ускорителя и успевает восстановиться пробитый зазор. К настоящему времени новая система установлена на всех пяти каналах системы ВЧ-питания и успешно прошла испытания в течение ~ 700 часов непрерывной работы. В предлагаемой работе обсуждаются особенности функционирования новой системы и приводятся результаты её испытаний. Раніше розглянуто особливості роботи паралельного тиристорного захисту, призначеного для захисту від пробоїв потужних ламп у вихідних каскадах системи ВЧ-живлення початкової частини прискорювача. У цій системі при виникненні пробою через 10 мкс запускається тиристорна збірка, що здійснює повний розряд накопичувача в аноді модуляторної лампи. Запропоновано принципово нова послідовна система захисту, яка позбавлена недоліків існуючого паралельного тиристорного захисту, що використовує можливості модулятора з регульованою лампою. У новій системі захисту при виникненні пробою через 5…7 мкс відбувається замикання модуляторної лампи, з подальшим перериванням запуску на декілька секунд. За цей час зберігається настроювання резонатора прискорювача і встигає відновитися пробитий зазор. До теперішнього часу нова система встановлена на всіх п'яти каналах системи ВЧ-живлення і успішно пройшла випробування протягом ~ 700 годин безперервної роботи. У пропонованій роботі обговорюються особливості функціонування нової системи та наводяться результати її випробувань. 2010 Article Results of the INR DTL series crowbar system testing / A.I. Kvasha, Yu.M. Lopatnikov // Вопросы атомной науки и техники. — 2010. — № 3. — С. 13-17. — Бібліогр.: 5 назв. — англ. 1562-6016 http://dspace.nbuv.gov.ua/handle/123456789/17004 en Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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Физика и техника ускорителей Физика и техника ускорителей |
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Физика и техника ускорителей Физика и техника ускорителей Kvasha, A.I. Lopatnikov, Yu.M. Results of the INR DTL series crowbar system testing |
| description |
In the earlier paper description of existing at INR DTL crowbar system and some proposals, increasing its efficiency, were considered. Really it was a question of replacement of the bypass crowbar by the series crowbar system. The last one can be used as RF exciting of accelerator cavities is realized by means of vacuum tube power RF amplifier (PA) with plate pulse supply. At that, vacuum tube has to be used in the anode modulator regardless of the method of RF power control. For the last year the new series crowbar system, using the possibilities of the "hard" modulator, was installed at all DTL RF systems of the INR accelerator. The system was successfully tested during 700 hours of continuous accelerator operation. Some peculiarities and results of new system functioning are discussed. |
| format |
Article |
| author |
Kvasha, A.I. Lopatnikov, Yu.M. |
| author_facet |
Kvasha, A.I. Lopatnikov, Yu.M. |
| author_sort |
Kvasha, A.I. |
| title |
Results of the INR DTL series crowbar system testing |
| title_short |
Results of the INR DTL series crowbar system testing |
| title_full |
Results of the INR DTL series crowbar system testing |
| title_fullStr |
Results of the INR DTL series crowbar system testing |
| title_full_unstemmed |
Results of the INR DTL series crowbar system testing |
| title_sort |
results of the inr dtl series crowbar system testing |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| publishDate |
2010 |
| topic_facet |
Физика и техника ускорителей |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/17004 |
| citation_txt |
Results of the INR DTL series crowbar system testing / A.I. Kvasha, Yu.M. Lopatnikov // Вопросы атомной науки и техники. — 2010. — № 3. — С. 13-17. — Бібліогр.: 5 назв. — англ. |
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2025-07-02T18:18:37Z |
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2025-07-02T18:18:37Z |
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| fulltext |
RESULTS OF THE INR DTL SERIES CROWBAR SYSTEM TESTING
A.I. Kvasha, Yu.M. Lopatnikov
Institute for nuclear research RAS, Moscow, Russia
E-mail: kvasha@inr.ru
In the earlier paper description of existing at INR DTL crowbar system and some proposals, increasing its effi-
ciency, were considered. Really it was a question of replacement of the bypass crowbar by the series crowbar
system. The last one can be used as RF exciting of accelerator cavities is realized by means of vacuum tube power
RF amplifier (PA) with plate pulse supply. At that, vacuum tube has to be used in the anode modulator regardless of
the method of RF power control. For the last year the new series crowbar system, using the possibilities of the
"hard" modulator, was installed at all DTL RF systems of the INR accelerator. The system was successfully tested
during 700 hours of continuous accelerator operation. Some peculiarities and results of new system functioning are
discussed.
PACS: 29.17.+w
1. INTRODUCTION
The necessity of crowbar system is caused by the
danger of powerful vacuum tubes damage due to break-
down of anode-grid gap and full discharge of the modu-
lator supply storage capacities. At the INR linear accel-
erator there are two high-priced powerful vacuum tubes,
which have to be protected from breakdowns by means
of crowbar system: anode modulator output triode GMI-
44A and RF output power amplifier (PA) triode GI-54A
or GI-71A, which last time is a substitute for GI-54A
[2]. However, as follows from long-term observations,
the overwhelming part of the breakdowns takes place in
the anode-grid cavity of the PA; hence, the crowbar sys-
tem also considerably reduces damages of the anode-grid
cavity surface due to breakdowns. View of inner surface
of the PA coaxial anode-grid cavity after long-term op-
eration is a strong evidence of the breakdown conse-
quence. Reasons of breakdowns are different and con-
nected with over voltages in the PA anode-grid cavity,
appearing at the rising and falling edges of RF pulse [3],
and with breakdowns in the coaxial transmitting line or
in the accelerator cavity. It follows to mention that very
often the breakdowns in the PA cavity are initiated by
burning of contacts in tuning devices or in butt joints.
There are a few well-known methods of breakdown
voltage increasing in PA cavities and transmitting lines
but each of them greatly complicates the design, opera-
tion and repair of the RF system. That is why the opera-
tion of the INR DTL RF system is protected by crowbar
system only. Below the main peculiarities of the bypass
and series crowbar systems are considered in detail.
2. BYPASS CROWBAR SYSTEM
The bypass crowbar system (BCS), presented in
Fig.1, had been in operation for 20 years. As a storage
device in the modulator high voltage supply artificial
forming line (AFL) with impedance 24 Ohm and time
discharge 400 μs had been installed. The AFL imped-
ance limits the value of breakdown current and that al-
lows using thyristors with current near 1 kA as the dis-
charge device. In turn, the discharge device consists of
110 thyristors in series for fast discharge of the AFL
capacities and dissipation of the energy, accumulated in
the storage. In Fig.1 the high voltage supply circuit is
shown, where IVR − induction voltage regulator, HVR −
high voltage rectifier, CB − high voltage circuit breaker,
CP-current protection relay. The last one is in series
with the HVR choke and protects the rectifier from the
current load, exceeding the set point value SP1. More-
over, in Fig.1 the main components of the amplitude
feedback are shown: amplitude detector AD, signal
from which is compared with set point value SP2, sum-
marizes with that of and after PI controller comes at the
premodulator (modulator driver) input. The pulse trans-
former between the premodulator and the modulator
vacuum tube GMI-44A separates high and low voltage
circuits.
Fig.1 Block-scheme of the DTL RF system
with the bypass crowbar system
Operation of the crowbar system starts in result of
exceeding of current transformer (CT1) output signal
the set point value SP3. Value of the set point, as a rule,
is twice higher than load current − dc component of
current through RF power amplifier vacuum tube. With
delay 15…20 ms after starting of the BCS thyristors
high voltage breaker CB opens the high voltage circuit
between the induction regulator IVR and the rectifier
HVR. Without BCS operation the breaker is controlled
by the current protection relay but with greater delay −
(80…100) msec. The necessity of fast switching off the
high voltage supply circuit by means of CB is connected
with peculiarity of BCS. The point is that operation of
the crowbar system really results in short circuit of high
voltage rectifier during discharge of the AFL. At that
dangerous over voltage in the storage capacities appears
due to the high value of choke inductance (12 H) at the
HVR output. In Fig.2 results of modeling by means of
Micro Cap 7, which are in good agreement with meas-
urements, are presented [1].
In Fig.2 upper trace corresponds to AFL voltage dur-
ing RF system operation with repetition rate 50 Hz and
____________________________________________________________
PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. 2010. № 3.
Series: Nuclear Physics Investigations (54), p.13-17.
13
mailto:kvasha@inr.ru
pulse length 400 μs right up to the crowbar starting,
after which switching off RF system operation occurs.
Fig.2. Over voltage in the AFL in result
of the bypass crowbar system operation
Lower trace shows high voltage rectifier current.
One can see that after discharge of the AFL in result of
the BCS operation recovery of the AFL capacities
charge takes place with ~ 50% over voltage. Maximum
value of the over voltage is achieved in ~30 ms and
maximum value of rectifier current in ~ 15 ms after
crowbar starting. Thus, the AFL recovers its charge for
one period and, despite of HV supply opening, break-
downs can repeat if only modulator driving won’t be
switched off right away after BCS operation. It is sig-
nificant that the maximum value of current nearly four
times exceeds the previous one and can be a reason of
CP relay operation. Thus, opening (by means of CB)
high voltage supply circuit in 15…20 ms after BCS op-
eration allows avoiding the dangerous over voltage and
reducing a possibility of breakdowns in the anode mod-
ulator due to the over voltage. So, each time after BCS
operation the modulator HV supply of the RF channel is
switched off and beam accelerating is stopped. Recov-
ery of the RF channel takes place only in 15…20 min
due to long process of the DTL cavity warming up after
switching off RF channel [4]. That is why any operation
of the bypass crowbar system results in decreasing of
the efficiency accelerator operation as a whole.
During all previous years the behavior of the bypass
crowbar system was carefully studying and a few modi-
fications have been done, directed at improving of the
crowbar system operation and decreasing of the false
operation:
• "Temporal gates” had been installed at the premodu-
lator (see fig.1) input to exclude a false drive of the
modulator, which could be a reason of a false opera-
tion of the BCS.
• A part of the equipment had been shifted from the
AFL location closer to the vacuum tube GMI-44A
and the control devices, so that to decrease a cou-
pling between high and low voltage equipment.
• The structure of the AFL was changed in order to
provide for the reliable cutoff of the thyristors after
the AFL discharge [1, 5].
• Interference immunity to false drive of the scheme,
opening the thyristors, was increased.
Nevertheless, the significant improvement in the
BCS operation hasn’t been achieved. At that, it was
occurred that the most part of BCS starting didn’t con-
nect with the real breakdowns in the modulator and RF
power amplifiers vacuum tubes but were caused by false
pickups. And there are a whole series of reasons, ex-
plaining this occurrence. Let’s mention the main ones.
• Accommodation of the devices, controlling thyristors
of the BCS, directly near high voltage charged AFL.
• Long length of communication between different
parts of the DTL RF channel. At that, separation of
high-current and low-current circuit communications
is often lacking.
• Separation of the grounding networks for measuring
and power devices is also lacking. So large value of
current in the common grounding networks might be
a source of disturbances for the control and measur-
ing equipments.
• Large values of the high voltage supply disturbances
in result of BCS operation in one from the RF chan-
nels. That can be a reason of over voltages and
breakdowns in the near by RF channels almost si-
multaneously with the first one.
• Availability of common for all RF channel systems,
such as the master oscillator and pulse synchroniza-
tion, by way of which a stray coupling between RF
channels can appear.
• Operation of a hundred high-speed thyristors in se-
ries during discharge of the AFL can be a source of
disturbances.
Accumulated long experience has allowed getting
over to new series crowbar system (SCS).
3. SERIES CROWBAR SYSTEM
Conversion from the bypass to the series crowbar
system wasn’t spontaneous one. First of all in the
framework of the BCS a possibility of the fast circuit
breaker CB switching off from current transformer CT1
(see Fig.1) was considered. At that, after discharge of
the AFL (in result of BCS operation), driving of the
anode modulator was interrupted during a few sec. Dur-
ing this time, on the one hand, accelerator cavity detun-
ing wouldn’t exceed 5…10% cavity pass band and, on
the other hand, a broken gap had time for recovery. In
this case starting of the BCS wouldn’t be accompanied
by a long (a few minutes) interruption of the accelerator
operation. But, as follows from Fig.2, CB switching off
results in increasing of the current protection relay (CP)
set point SP1 in a few times, so that the BCS operation
wasn’t accommodated by high voltage supply opening
and long interruption of the accelerator operation. Thus,
the attempt to shorten the accelerator downtown during
BCS operation resulted in decreasing of the current pro-
tection sensitivity and 50% GMI-44A plate over voltage
(see Fig.2).
The next step assumed the full switching off of the
BCS; at occurrence of breakdown (during RF pulse)
driving of the anode modulator was interrupted for a
few second, beginning with the next pulse. As in previ-
ous case during this time accelerator cavity detuning
would change insignificantly and ionization in broken
gap would be decreased to the extent that the repeated
14
15
nal from the CT1
exc
breakdown (after recovery of the modulator driving)
wouldn’t appear. But the tests showed that response of
the HV supply at the breakdown didn’t differ from that
of at the BCS thyristors starting. In both cases full dis-
charge of the AFL took place. It means that the depend-
encies, presented in Fig.2, are also true in a case of
breakdowns with switched off BCS. Moreover, for re-
alization of the system it is need to decrease the sensi-
tivity of the current protection relay CP.
It follows also to add that though limiting of the
breakdown current (by the AFL impedance), the most
part of the energy, accumulated in the AFL, is dissi-
pated in the broken gap. In the INR DTL RF system
value of energy, stored in the AFL, nearly twice exceeds
the energy, consumed from the AFL during regular op-
eration. So, even the single breakdown can result in a
damage of the RF equipment.
The next evident step consisted in increasing of op-
erating speed during interruption of the anode modula-
tor driving. The case in point is interruption of modula-
tor driving in limits of RF pulse, so that the breakdown
appearance didn't result in to full discharge of the AFL.
For this purpose the modulator vacuum tube, connected
in series with the load – RF output power amplifier (PA)
vacuum tube, can be successfully used. The point is that
the output PA is the final-control of the amplitude con-
trol system, stabilizing the amplitude of RF voltage in
the accelerator cavity. There are two methods of the RF
power control: by means of the PA plate pulse voltage
control or by means of the RF exciting control at the
input of the PA. In both cases there is a necessity of the
PA plate control by means of the fast-acting "hard"
modulator with vacuum tube: it is obviously for the first
way of power control and not entirely for the second.
But if to take into account changing of PA vacuum tube
current dc component at the RF exciting control (due to
operation with cutoff angle) it is become evident a ne-
cessity of the PA plate supply stabilization by means of
the “hard” modulator. Hence, the PA plate modulator
can fulfill two functions: control or stabilization of the
modulator pulse amplitude and fast protection of all
networks, which are under high voltage pulse, including
RF amplifier vacuum tube and anode-grid cavity, from
breakdowns. Such is indeed an operation of the series
crowbar system SCS. There are two main advantages of
the system:
• A lack of the additional devices in the anode modu-
lator high voltage supply.
• Starting of the SCS doesn’t results in discharging of
the artificial forming line AFL and long interrupting
of accelerator operation.
• As the AFL doesn’t discharge the AFL the SCS op-
eration isn’t a source of disturbances for other DTL
RF system channels and, hence the quantity of false
crowbar starting has to be decreased.
The simplified block scheme of the INR accelerator
DTL RF channel with series crowbar system and ampli-
tude feedback is presented in Fig.3. The system involves
the next additional devices:
• the current transformer CT1, signal of which comes
to comparator;
• two single shot multivibrators M1 and M2;
• two logic units AND and NAND.
If, in result of breakdown, the sig
eeds the set point value SP3, a single shot multivi-
brator M1 changes the state and locks the premodulator
input during a few sec. Transients in premodulator and
pulse transformer (see Fig.3) determine a time delay
between premodulator and modulator vacuum tube
locking and its value can achieve a few μs.
Fig.3. Block-scheme of the DTL RF channel
with the series crowbar system
falling edge of multivibrator In turn, M1 pulse
cha
R
By now, the se SCS, which can
be
nges the state of multivibrator M2 with the similar
pulse length. If during this time the second breakdown
takes place, high voltage is entirely switched off by
means of the high voltage breaker CB. SP1 and SP2
values determine the permissible high voltage rectifier
HVR current and the control level of RF voltage in the
accelerator cavity. All above-listed additional devices,
realizing operation of the SCS, are placed at a short dis-
tance from each other, far off the high voltage equip-
ment. That considerably decreases the level of distur-
bances from its own and other DTL RF channels.
4. RESULTS OF THE SERIES CROWBA
SYSTEM TEST
ries crowbar system
also named as Interruption and Delay Crowbar
System, has been in operation for 700 hours. It was
installed at all five regular DTL RF channels and results
of its operation exceeded all expectations. First of all,
the downtime of the accelerator operation due to the
DTL RF system defaults has been considerably (a few
times) shortened in comparison with the previous
bypass crowbar system. Then, simultaneous crowbar
system starting in two and more RF channels, so
frequent before, were lacking during all time of the SCS
observation. Moreover, the common quantity of the
crowbar starting in the RF channels was also decreased.
All that confirmed the previous statement that the
bypass crowbar system (BCS) was more subjected to
disturbances in comparison with the series one. Effi-
ciency of the new series crowbar system was particu-
larly showed itself during the last two sessions of the
accelerator operation. Before the first session the new
vacuum tube GI-71A was installed in the output power
amplifier of the RF channel # 4. Due to bad vacuum in
the GI-71A, operation of the PA was accompanied by
permanent inner breakdowns, common amount of which
exceeded 1000. With the previous bypass crowbar
system operation of the accelerator would be paralyzed.
With the series crowbar system both sessions were
successfully completed.
In Fig.4 shots of PA vacuum tube GI-71A plate cur-
rent (upper trace) and pulse plate voltage (lower trace)
are shown. Inrush of the plate current was due to the PA
vacuum tube GI-71A breakdown. As it was mentioned
above, the SCS operation width depends on transients in
the premodulator and pulse transformer at its output.
16
Fig.4. Processes during series crowbar operation
Just these devices determine duration of the break-
down. One can see that at once after the breakdown
plate voltage pulse was shortened and duration of the
breakdown didn’t exceed 7…8 μs. During this time only
one (the first) capacity of the AFL from 20 had time to
discharge [1].
In Fig.5 the shots of processes during series crowbar
operation are presented in detail – time scale was
changed from 25 μs/dev (in Fig.4) to 1 μs/dev.
Fig.5. Processes during series crowbar
system operation in detail
From the last shot pictures it follows that the process
during SCS operation is accompanied by oscillations
both of current and modulator pulse amplitudes. At that,
the oscillations at both traces are in antiphase and the
oscillation frequency value is a few times higher than
modulator bandwidth. One could suppose that the
breakdown current is interrupted when plate pulse volt-
age falls to the low value and appears again when it
rises. The reasons of this phenomenon can be different
ones. First of all, it follows to take into account that at
all electrodes in the RF power amplifier, where break-
downs can appear, both pulse voltage and RF voltage
exists. It is true for the vacuum tube and DTL PA an-
ode-grid cavity. In the PA cavity structure (so called
half-wave length coaxial cavity) is lacking isolating
capacity, which bypasses RF around high voltage sup-
ply input. Hence, the inner stem of the PA cavity is both
under high pulse voltage plate and RF voltage in the
cavity, which amplitude can up to 10 times exceed plate
supply voltage and achieves 300 kV. The breakdown
appears as the result of the total action of both compo-
nents. At that, due to voltage drop at the high voltage
source (AFL) internal resistance, both components of
the voltage fall to such extent that the breakdown can be
interrupted up to that moment when plate voltage again
will achieve the previous value. So, the observed oscil-
lations frequency (see Fig.5) could be result of tran-
sients in the long coaxial cable (up to 50 m), connecting
the AFL and the modulator valve GMI-44A, or in the
low quality PA cavity. The issue remains open.
CONCLUSIONS
Results of new series crowbar system testing showed
that the system allows successfully protecting from
breakdowns the RF power amplifier vacuum tube and
PA anode-grid cavity. Just here, in the main, break-
downs take place. Breakdowns in the modulator vacuum
tube GMI-44A, as a rule, occur during time between RF
pulses, when the plate voltage has maximum value. As
between RF pulses PA vacuum tube internal resistance
exceeds 1kOhm, the breakdown current value can't re-
sult in to the modulator vacuum tube damage.
REFERENCES
1. A.I. Kvasha, V.L. Serov. Development of the INR
DTL RF System Crowbar Operation // Proc. of
RUPAC 2008. Zvenigorod, Russia, p.218.
2. A.I. Kvasha, et al. A new 200 MHz Powerful Pulse
Triode for the Output Power Amplifier of the DTL
RF System // Proc. of PAC2001. Chicago, Illinois,
USA, p.1225.
3. A.I. Kvasha. Analog computation of transients in the
Power Amplifier of DTL RF System // Problems of
Atomic Science and Technology. Series "Nuclear
Physics Investigations" (43). 2004, №2, p.81.
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Simulation of the INR RAS DTL frequency stabili-
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Статья поступила в редакцию 07.09.2009 г.
17
РЕЗУЛЬТАТЫ ИСПЫТАНИЙ ПОСЛЕДОВАТЕЛЬНОЙ ЗАЩИТЫ СИСТЕМЫ
ВЧ-ПИТАНИЯ НАЧАЛЬНОЙ ЧАСТИ УСКОРИТЕЛЯ ИЯИ РАН
А.И. Кваша, Ю.М. Лопатников
Ранее рассмотрены особенности работы параллельной тиристорной защиты, предназначенной для защи-
ты от пробоев мощных ламп в выходных каскадах системы ВЧ-питания начальной части ускорителя. В этой
системе при возникновении пробоя через 10 мкс запускается тиристорная сборка, осуществляющая полный
разряд накопителя в аноде модуляторной лампы. Предложена принципиально новая последовательная сис-
тема защиты, лишённая недостатков существующей параллельной тиристорной защиты, использующая
возможности модулятора с регулируемой лампой. В новой системе защиты при возникновении пробоя через
5…7 мкс происходит запирание модуляторной лампы с последующим прерыванием запуска на несколько
секунд. За это время сохраняется настройка резонатора ускорителя и успевает восстановиться пробитый
зазор. К настоящему времени новая система установлена на всех пяти каналах системы ВЧ-питания и ус-
пешно прошла испытания в течение ~ 700 часов непрерывной работы. В предлагаемой работе обсуждаются
особенности функционирования новой системы и приводятся результаты её испытаний.
РЕЗУЛЬТАТИ ВИПРОБУВАНЬ ПОСЛІДОВНОЇ СИСТЕМИ ЗАХИСТУ
ВЧ-ЖИВЛЕННЯ ПОЧАТКОВОЇ ЧАСТИНИ ПРИСКОРЮВАЧА ІЯД РАН
А.І. Кваша, Ю.М. Лопатников
Раніше розглянуто особливості роботи паралельного тиристорного захисту, призначеного для захисту від
пробоїв потужних ламп у вихідних каскадах системи ВЧ-живлення початкової частини прискорювача. У цій
системі при виникненні пробою через 10 мкс запускається тиристорна збірка, що здійснює повний розряд
накопичувача в аноді модуляторної лампи. Запропоновано принципово нова послідовна система захисту, яка
позбавлена недоліків існуючого паралельного тиристорного захисту, що використовує можливості модуля-
тора з регульованою лампою. У новій системі захисту при виникненні пробою через 5…7 мкс відбувається
замикання модуляторної лампи, з подальшим перериванням запуску на декілька секунд. За цей час зберіга-
ється настроювання резонатора прискорювача і встигає відновитися пробитий зазор. До теперішнього часу
нова система встановлена на всіх п'яти каналах системи ВЧ-живлення і успішно пройшла випробування
протягом ~ 700 годин безперервної роботи. У пропонованій роботі обговорюються особливості функціону-
вання нової системи та наводяться результати її випробувань.
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